"UK experts are backing the call for flour to be fortified with folic acid – a move which they say would have prevented about 2,000 cases of serious birth defects since 1998," BBC News reports.
Folic acid supplementation around the time of conception and early pregnancy is known to help the formation of a baby's brain and spinal cord. It also reduces the risk of a baby being born with neural tube defects, the most common being spina bifida.
The compulsory fortification of flour with folic acid was introduced in the US and 77 other countries in 1998. The UK chose not introduce the policy, opting to advise women to take supplements instead.
Researchers looked at health records to see how many cases of neural tube defect there have been in the UK over the past 15 to 20 years, and estimated how many there might have been had flour fortification been introduced.
Their results suggest there would have been around 21% fewer babies born with neural tube defects since 1998 – around 2,000 babies.
Current UK recommendations are that women who are pregnant, thinking of trying to have a baby or likely to become pregnant should take a 0.4mg (400 micrograms) folic acid supplement until the twelfth week of pregnancy.
This reliable and informative research has added to the weight of evidence to bring about a change in policy.
In recent months the Food Standards Agency, the Scientific Advisory Committee on Nutrition and the Chief Medical Officer for England, Dame Sally Davies, have all called for the policy to be changed.
Concerns have been raised that folic acid increases the risk of some types of cancer.
But a major study in 2013 looked at around 50,000 people who had been randomly assigned to take folic acid or not for at least one year.
It found folic acid supplementation taken at recommended levels carried no significant influence on the risk of any type of cancer.
The study was carried out by researchers from Queen Mary University of London and other UK universities, and Public Health England and Public Health Wales.
No sources of funding are reported and the authors declared no conflicts of interest.
The UK media provided reliable coverage of this study, with the BBC reporting that the Department of Health is "currently considering the matter".
This study used registry data from England and Wales to identify children born with birth defects over a roughly 20-year period.
They looked at the proportion of women taking folic acid supplements before pregnancy, and estimated how many defects could have been prevented if folic acid was effectively available to all in the form of flour, without the need for supplements.
Folic acid – vitamin B9 – is needed around the time of conception and in the early stages of pregnancy to prevent birth defects, in particular spina bifida.
This is the most common of a group of conditions called neural tube defects (NTDs), where the spinal cord has not formed properly.
In 1991 a key study reportedly found taking folic acid supplements before pregnancy reduced the risk of NTDs by around 72%.
While folate is naturally present in certain foods, such as leafy green vegetables, it is not possible to get adequate amounts from natural food sources alone.
Ways round this are by women either taking folic acid supplements or eating foods like bread or wholegrains that have been fortified with folic acid.
The compulsory fortification of flour was introduced in several countries, including the US, Canada and Australia, but has not been made compulsory in the UK.
In 1992, women in the UK were instead advised to take folic acid supplements before pregnancy to reduce the risk of NTDs. But how often does this actually happen – especially as many pregnancies are unplanned?
This study used data from a number of sources to look at how many babies were born with NTDs in the UK. The researchers did this so they could estimate what the effect would have been if the compulsory fortification of flour with folic acid had been introduced here in 1998, as it was in the US.
The researchers gathered data from eight birth defect registers covering England and Wales to determine the number of babies born with NTDs between 1991 and 2012.
To estimate the number of NTDs across the UK in any given year, the researchers looked at the prevalence in those regions covered by a register and multiplied these figures by the total number of births in the UK in that year.
A recent study assessing folic acid supplementation in almost half a million women in England suggested around 39.6% of women in 1999 took folic acid supplements around the start of pregnancy, but this declined to only 27.8% in 2012.
These figures are in close agreement with another UK study, which suggested around a quarter of women took folic acid supplements before pregnancy between 2009 and 2012.
To calculate a conservative estimate of the effect fortifying flour would have had, the researchers assumed this would only have benefited pregnant women who did not take supplements. They also calculated that 28-40% of women would take supplements, rather than the lower estimate of only 25%.
Between 1991 and 2012, 1.28 per 1,000 pregnancies (95% confidence interval [CI] 1.24 to 1.31) had a baby affected by an NTD.
The majority of pregnancies identified to have a baby with an NTD were terminated (81%), and 0.5% resulted in foetal death at 20 weeks of pregnancy and above or a stillbirth.
When only looking at live births, 0.20 per 1,000 live babies born in the UK had an NTD (95% CI 0.16 to 0.25).
After women were recommended to take folic acid supplements in the UK, between 1998 and 2012 there was a non-significant 7% decrease in the number of babies born with NTDs in the UK.
The researchers calculated that, had compulsory flour fortification been introduced here in 1998 as in the US, there would have been an estimated 2,014 fewer pregnancies affected by an NTD across the UK.
This would have meant a 21% reduction in the number of babies affected by an NTD over this time period, rather than the roughly 7% decrease observed with the recommendation to take folic acid supplements.
The researchers concluded: "Failure to implement folic acid fortification in the UK has caused, and continues to cause, avoidable terminations of pregnancy, stillbirths, neonatal deaths and permanent serious disability in surviving children."
The time around conception and the first 12 weeks of pregnancy are known to be an important time for the development of the brain and spinal cord. Crucially, folic acid supplementation at this time is known to decrease the risk of defects such as spina bifida.
In the US, the compulsory fortification of flour with 140mg of folic acid per 100g of enriched cereal grain product was introduced in 1998. This has been estimated to provide 200mg of folic acid per day to women of childbearing age.
In the UK, the decision was not made to fortify flour, but since 1992 the government instead recommended that women take 400 micrograms of folic acid each day before pregnancy and for the first 12 weeks of pregnancy, when the spinal cord is forming.
However, previous research suggested only around one-quarter to one-third of UK women actually take folic acid supplements as recommended around the start of pregnancy.
This research demonstrates that 1.28 per 1,000 pregnancies in the UK over roughly the past 20 years has been affected by an NTD. Most of these babies have resulted in termination or foetal death, with far fewer – 0.20 per 1,000 babies – actually born living with an NTD.
Although the absolute risk of having a baby affected by an NTD is quite low, the results suggest it could have been around 21% lower since 1998 if compulsory flour fortification had been introduced. Advising women to take supplements has only led to around a third of the size of this reduction over the same time period.
There are many reasons why only a low proportion of women may take folic acid supplements as recommended. The most obvious reason is not all pregnancies are planned and many women may not realise they are pregnant for several weeks, missing the crucial period for spinal cord development.
Fortification of flours and grain could try to help ensure that, in effect, everyone in the population is covered. As the researchers say, it is a safe vitamin for all that has not been shown to be associated with any harms. Other studies are also said to have demonstrated that the fortification of flour with folic acid is a cost-effective measure.
However, there may still be the possibility that some childbearing women could still receive suboptimal folic acid even with compulsory flour fortification – for example, depending on how much bread or flour-containing products they eat.
This is reliable and informative research that has used a number of national birth defect registers, and attempted to make conservative estimates that allow for the highest number of women taking folic acid supplements as recommended.
Overall, the study estimates around 2,000 fewer pregnancies over the past 20 years would have been affected by NTDs like spina bifida if flour fortification had been introduced. But this is still only an estimate that relies on various assumptions.
The researchers suggest the fortification of flour with folic acid should be a priority for public health policy in the UK.
It is not yet known whether policy around flour fortification will change as a result of this study, but it will undoubtedly need to be reconsidered, especially as it follows similar recommendations made recently by the Scientific Advisory Committee on Nutrition and England's Chief Medical Officer.
For now, the recommendation stands that women planning a pregnancy should take 400 micrograms of folic acid daily, as well as in the first 12 weeks of pregnancy.